/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.yarn.server.resourcemanager.scheduler.placement;

import org.apache.hadoop.yarn.server.resourcemanager.scheduler.SchedulerNode;

public class PlacementSetUtils {
  /*
   * If the {@link PlacementSet} only has one entry, return it. otherwise
   * return null
   */
  public static <N extends SchedulerNode> N getSingleNode(PlacementSet<N> ps) {
    N node = null;
    if (1 == ps.getAllNodes().size()) {
      node = ps.getAllNodes().values().iterator().next();
    }

    return node;
  }
}
